In conventional integrated circuit (IC) design, it can be difficult to measure and/or monitor negative voltages. This problem is made worse as the magnitude of those negative voltages increases (e.g., less than −8 volts (V)). Existing measurement techniques generally use either large resistor dividers and/or additional IC pins to make the negative voltage available and directly observable by an external sensor. In the case of a resistor divider, though, low-power charge pumps are generally not able to provide sufficient current to drive a resistor divider. External pins require the capability to pass a negative voltage, which complicates the design of electro-static discharge (ESD) structures connected to the IC and require significant additional space within the IC.
In some cases, existing circuits use Zener diodes to provide a predetermined offset to a measurement of a negative voltage (enabling the negative voltage to be measured as a positive voltage with known offset using conventional techniques). However, in many cases, existing fabrication techniques, such as silicon metal oxide semiconductor techniques, cannot bias Zener diodes to a sufficient degree to measure negative voltages below −8 V. Additionally, the use of an offsetting Zener diode consumes energy from the voltage node being measured.